{ null null rot
  { dup null? not }
  { uncons swap rot cons -rot } while drop
} : split
variable 'sort  variable 'merge  variable 'compare       
{ 'sort @ execute } : sort
{ 'merge @ execute } : merge
{ 'compare @ execute } : compare
' < 'compare !
{ dup null? { drop } {
    over null? { nip } {
      over car over car compare ' swap if
      uncons rot merge cons
    } cond
  } cond
} 'merge !
{ dup null? {
    dup cdr null? {
      split sort swap sort merge
    } ifnot
  } ifnot
} 'sort !
3 1 4 1 5 9 2 6 5  9 list
dup .l cr sort .l cr
"once" "upon" "a" "time" "there" "lived" "a" "very" "little" "kitten"  10 list
{ $cmp 0< } 'compare !
dup .l cr sort .l cr